I'm pretty sure people can provide links, because I can only remember the Bill Nye incident, but basically the majority of things Snopes investigates that come up as false typically are of right-leaning nature and they barely earn the title "false"
are you mixing snopes and politifact here? i'd like to see data on this, cus it seems like a very large portion of the things snopes covers are just dumb misinformed social media posts and the sort, rather than focusing on politics like politifact does
i found the article you're talking about, and their evaluation is specifically because the quote isn't real and it oversimplifies what was being said, and in the context of where the image would be applied, inaccurately represents nye's views
http://www.snopes.com/bill-nye-gender-chromosomes/ they also do make specific mention of the co-star you're talking about, maybe this was edited onto the article after people found it
though in the grand scheme of things, it's obviously not nearly enough to substantiate a claim of bias. the fact still stands that snopes' format forces itself to provide sources that point to verifiable truths that objectively disprove or verify something. they aren't a news source that people go to for new information either, they're a rhetorical tool, so a selection bias argument seems irrelevant here as well. if snopes provides sufficient evidence that something is true or false, then what's the issue? i don't go to snopes to see what's new in the world, i go there because someone made specific mention of something and i want to see if i can verify it. and for that purpose, per-article accuracy is far more important than whatever selection they have available, and since they source all their points and explain in-detail why something is or isn't true, i think it hits that mark just fine.
note: made lots of edits, sorry if there was a response happening as i made them
